Long-Term Debt and Common Stock (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Debt Instrument Table [Line Items]
Total Long-Term Debt	$ 5,040,000,000		$ 5,040,000,000
Total Long-Term Debt, Net	5,010,523,000		5,009,166,000
Debt Instrument, Maturity Date	Oct. 11, 2016
After-tax net impact from interest rate swap	400,000	1,000,000
Debt Instrument Issuance [Abstract]
Debt Instrument Issuance Face Value	150,000,000
Line of Credit Facility [Line Items]
Weighted average interest rate (in hundredths)	0.38%
Average Borrowings Outstanding	59,000,000
Common Stock Dividends Declared	$ 0.17	$ 0.16
Revolving Credit Agreement 2011 [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	2,000,000,000
Outstanding balance	$ 0
Eurodollar rate at period end (in hundredths)	1.12%
Base rate at period end (in hundredths)	3.25%